usb: gadget: Support G-Link for GPS function driver

The existing GPS function driver uses SMD transport
to communicate with the modem. SMD is deprecated on
newer targets. Add support for G-Link transport for
the GPS function driver to communicate with the modem.

Stats of the G-Link channels can be seen by using the
below command
cat /sys/kernel/debug/usb_glink_ctrl/status
The stats can be reset by writing to the same node
echo 0 > /sys/kernel/debug/usb_glink_ctrl/status

CRs-Fixed: 2121744
Change-Id: Id2e84292e1cd1a08499c23604f9c9efe02f5fbe5
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>